Divisions of the Brain

FOREBRAIN

 - CEREBRUM  (Telencephalon)

 - THALAMUS   (Diencephalon)

HINDBRAIN

 - BRAINSTEM

     - Medulla  (Myelencephalon)

     - Pons  (Metencephalon)

     - Midbrain  (Mesencephalon)

 - CEREBELLUM (Metencephalon)

Ischemic Stroke

-85% of all strokes (15% Hemorrhage)            

-Occlusive Vascular Disease

- Hypotension

Occlusive Vascular Disease

-OCCLUSIVE  VASCULAR  DISEASE

 AFFECTS  MAINLY

 LARGE   ARTERIES

Chronic Hypertension

-CHRONIC   HYPERTENSION

Affects  mainly

 SMALL   ARTERIES

ISCHEMIC STROKE DUE TO HYPOTENSION.....

-ISCHEMIC STROKE DUE TO HYPOTENSION AFFECTS WATERSHED AREAS THE MOST

Glutamate Cytotoxicity 

-Reduced oxygen levels during

ischemia elevate extracellular

glutamate. As a result, post-

synaptic neurons take up     

large amounts of  calcium  

ions and die.

This process  also results in a delayed  ( weeks or even months )   loss of  neurons through  apoptosis in more peripheral regions with milder ischemia.                               

SACCULAR (Berry)

CEREBRAL

ANEURYSMS

-Anterior Circulation

85%

-Posterior Circulation

15%

NERVES MOST VULNERABLE TO

ANEURYSM COMPRESSION

-Optic

-Oculomotor

-Trochlear

-Abducens

- Trigeminal

   (Ophthalmic)

ARTERIOVENOUS  MALFORMATION

A congenital tangle of arteriovenous connections, with no intervening capillaries, which grows  and  robs the brain of its blood supply (Ischemia) and may cause seizures or hemorrhage due to high pressure in the vessels. (300,000 in USA; 12% present a problem)

EFFECTS OF HYPERTENSION

Small Arteries

           ↓

Lipohyalinosis:

Hyalinization and

lipid occlusion of

distal vessel 

            ↓

LACUNAR INFARCTS      &  MICROANEURYSMS

                                     (Potentially hemorrhagic)

Intracerebral  Hemorrhage

- Caused by ruptured microaneurysm